My style has changed over the years. Ive gone from park to freestyle to more freeride big mountain riding. Currently Im riding a 165 freestyle type board but I want something big and stiff and no Im not talking about trannys. I was thinking about an 170cm arbor aframe, but is there something even bigger and less flexy?

Birdman is not a long board as such, it's a 156 with a long nose added on for powder.
You need to look at effective edge and sidecut radius measurements to really get a good understanding of how "big" a board really is. On top of that you need to know exactly what features you want in a board, from the sound of it you are not looking for a powder stick but a carving machine. Donek do some nice race style boards as mentioned above, you could also look at the furberg 173 with 20m sidecut radius!Furberg Snowboards - Freeride 173

The more boards you try the more you get a feel for what you like and what you dont

Also take a look at the Kessler Ride 168. It's designed to be a big mountain/freeride board with a lot of good tech in it. Not cheap but I haven't heard a bad thing about Kesslers yet. I'm currently riding a Burton T7 159 which is super stiff, and I might switch to the Kessler if I find a good deal on one.

My style has changed over the years. Ive gone from park to freestyle to more freeride big mountain riding. Currently Im riding a 165 freestyle type board but I want something big and stiff and no Im not talking about trannys. I was thinking about an 170cm arbor aframe, but is there something even bigger and less flexy?